7. Dumortiera. Receptacle convex, 2–8-lobed. Perianth none.
1. MARCHÁNTIA, Marchant f. ([Pl. 22.])
Thallus large, forking, areolate, porose, with broad diffused midrib; gemmæ in a cup-shaped receptacle. Diœcious. Fertile receptacle peduncled from an apical sinus of the thallus, radiately lobed. Involucres alternate with the rays, membranous, lacerate, enclosing 3–6 1-fruited cleft perianths. Calyptra persistent. Capsule globose, exserted, pendulous, dehiscing by several revolute segments. Elaters long, attenuate to each end. Spores smooth. Antheridia immersed in a peduncled disk-like radiate or lobed receptacle. (Named for Nicholas Marchant, a French botanist.)
1. M. polymórpha, L. Thallus 2–5´ long, ½–1½´ wide, numerously porose, venulose; receptacle divided into usually 9 terete rays; peduncles 1–3´ high; antheridial disk crenately or palmately 2–8-lobed, on a peduncle 1´ high or less.—Everywhere common. (Eu.)
2. PREÌSSIA, Nees. ([Pl. 22.])
Thallus obcordate, sparingly forked, increasing by joints; pores conspicuous; gemmæ none. Diœcious or monœcious. Fertile receptacle hemispheric, 1–4-lobed, with as many alternating shorter rib-like rays. Outer involucres attached beneath the lobes, 1–3-fruited, opening outward by an irregular line; perianth obconic-campanulate, angular, unequally 4–5-lobed. Calyptra persistent. Capsule large, distinctly pedicelled, dehiscing by 4–8 revolute segments. Elaters short. Spores coarsely tuberculate. (Named for L. Preiss, a German botanist.)
1. P. commutàta, Nees. Thallus 1–2´ long, with conspicuous white pores above, and dark purple scales beneath; usually monœcious; peduncle ½–1´ high; capsules conspicuous, dark purple; antheridia in a peduncled disk-like receptacle. (P. hemisphærica, Cogn.)—On slaty and limestone rocks, from N. J. north and westward. (Eu.)
3. FIMBRIÀRIA, Nees. ([Pl. 22.])
Thallus thickened in the middle by a keeled costa, usually conspicuously porose, with dark purple scales beneath; gemmæ none. Monœcious. Receptacle rising from the apex, conic or hemispheric, concave beneath and expanded into usually 4 large campanulate 1-fruited involucres. Perianth oblong-oval or subconic, exserted half its length and cleft into 8–16 fringe-like segments. Calyptra with a long style, fugacious. Capsule nearly sessile, irregularly circumscissile. Elaters rather short, 1–4-spiral. Spores angular, subreticulated. Antheridia immersed in the thallus. (Name from fimbria, a fringe, alluding to the perianth.)
1. F. tenélla, Nees. Thallus of one or more long-wedge-shaped emarginate divisions about 6–9´´ long, grayish-green and porose above, purple on the margins; peduncle 1´ high or more, usually purple; receptacle obtusely conic; perianth white, 8-cleft.—On damp ground in sandy fields or on rocks, central N. Y. to Mo., and southward.